Find the measure of the missing leg

Which property is illustrated by the following statement? if hxa rgi, then rgi hxa.

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given

Which expression is a factor of 12x2 + 29x – 8? x – 8 2x – 1 3x + 8 4x + 1